Chrisa112 Posted February 3, 2013 Report Share Posted February 3, 2013 Right, some may have said this was inevitable... My CRF450R's engine went on Saturday. Happened at full chat in 5th gear whilst overtaking a car (whoops). It sounded like it was getting up towards the rev limit then it made a loud metallic rattle/crashing sound and cut out. Rear didn't lock up. No big smoke came out of engine or exhaust (not that I saw anyway). No obvious damage to the outside of the engine. No oil came out of the bike (although strangely there is no oil visible in the engine oil window...). Tried kicking it over slowly at road side and a fairly big puff of smoke came out from somewhere in the engine and it didn't sound healthy either. Obviously it didn't start either haha. I had thought the cam chain sounded a bit more rattley than usual just before it died but other than that everything seemed normal. Not had the head off yet so I'm just trying to get some initial thoughts on what it could be? Cheers, Chris Link to comment Share on other sites More sharing options...
Barry Posted February 3, 2013 Report Share Posted February 3, 2013 Dropped a valve and made a mess I'd bet! Link to comment Share on other sites More sharing options...
CMSMJ1 Posted February 3, 2013 Report Share Posted February 3, 2013 "tried kicking it over" oops... get your spanners out and lets see the carnage! Link to comment Share on other sites More sharing options...
porter_jamie Posted February 3, 2013 Report Share Posted February 3, 2013 Only one way to find out. Doesnt take long to rip the motor out and whip the head off. Link to comment Share on other sites More sharing options...
peter187 Posted February 4, 2013 Report Share Posted February 4, 2013 Just strip it down and have a look. It might give you an excuse to buy some fancy titanium valves. http://www.procircuit.com/intake-valve-cf450r-ft02-08.html Link to comment Share on other sites More sharing options...
2T Institue Posted February 4, 2013 Report Share Posted February 4, 2013 Right, some may have said this was inevitable... My CRF450R's engine went on Saturday. Happened at full chat in 5th gear whilst overtaking a car (whoops). It sounded like it was getting up towards the rev limit then it made a loud metallic rattle/crashing sound and cut out. Rear didn't lock up. No big smoke came out of engine or exhaust (not that I saw anyway). No obvious damage to the outside of the engine. No oil came out of the bike (although strangely there is no oil visible in the engine oil window...). Tried kicking it over slowly at road side and a fairly big puff of smoke came out from somewhere in the engine and it didn't sound healthy either. Obviously it didn't start either haha. I had thought the cam chain sounded a bit more rattley than usual just before it died but other than that everything seemed normal. Not had the head off yet so I'm just trying to get some initial thoughts on what it could be? Cheers, Chris Simple it's a four stroke Link to comment Share on other sites More sharing options...
YZ faybo Posted February 6, 2013 Report Share Posted February 6, 2013 Whip the rocker cover off and have a quick peep, have you had the head off recentley? when going back together the stock honda cam sprokets are not the best and idealy use new bolts when working on them as even with loctite can stretch and come loose. The honda cam chain tensioners are pretty good as stock and cam chains can last a whille but the guides do wear. Whats the plug look like? try and get some torch light down the plug hole and see if the top of the piston is damaged. Dont put titanium valves in, the stock titanium pair do strech and are stupid money, I used kibble white stainless in mine as in super moto you do generally hold onto higher revs for longer periods with more load than on the dirt. If you need spares go to the states I got a new head for £240 rather than the £400 quoted over here!! Link to comment Share on other sites More sharing options...
trackdaybob Posted February 6, 2013 Report Share Posted February 6, 2013 I thought Honda's didn't go bang? Surely it's an electrical problem ?? Link to comment Share on other sites More sharing options...
Chrisa112 Posted February 6, 2013 Author Report Share Posted February 6, 2013 Well had the rocker cover off a few days ago. Everything looked OK...except for two shims just sitting on the head in some oil (top left): So not sure what this means yet. Valves only use one shim each right, so have two valves dropped? Have the shims just somehow popped out? Faybo - Not had the head off since owning it. Was planning to Valve clearances in about 2/3 riding hours time. I'll whip the plug out tonight and get back to you regarding damage as I've not had time to get the head off yet. Aye, Crfsonly in America have been good to me so far regarding parts so will probs use them again. Cheers, Chris Link to comment Share on other sites More sharing options...
2Smoke Posted February 6, 2013 Report Share Posted February 6, 2013 Ooops... Maybe one has snapped the head, and a piece of it has become lodged in the neighbouring valve? Link to comment Share on other sites More sharing options...
Gix Posted February 6, 2013 Report Share Posted February 6, 2013 weakest point of a crf..valves One will have snapped and wedged open the other. I would say you have been extremely lucky. 99.9% of the time when a crf drops a valve it will snap the rod and then usually whats left of the rod will exit the cases..at the front if you are lucky, into the box if you are not..both if you are me(see pic) Aren't you the one who has DAZ's old CRF ? You WILL now have to change the rod, unfortunately edit..I know parts are cheaper stateside but before trying there give Mike Wright at MWRacing a call..he has a rake of new CRF parts on the shelf from brand new bikes which have had race motors put in em. He is a top guy too and won't have your pants down Link to comment Share on other sites More sharing options...
Chrisa112 Posted February 7, 2013 Author Report Share Posted February 7, 2013 Jesus, in comparison to that I DO feel lucky... Yes this is Daz' CRF. Don't understand why it has happened yet as I'm sure he had changed the valves to SS anyway. Maybe it was just a matter of time. Thanks for the heads up on MW racing too. Link to comment Share on other sites More sharing options...
Gix Posted February 7, 2013 Report Share Posted February 7, 2013 I doubt very much they are stainless but you did say you were flat out... You weren't anywhere near the limiter by any chance where you ? Over rev a 450 and you will get valve bounce. As the distance between piston crown and valve is minimal then valve bounce can cause a piston-valve interface bending the valve and snapping it. Good chance your head will be bolloxed and rod bent. As I have always said on SM Forum..if you buy a 450 crf for road, always get a set of stainless valves thrown in when you buy, unless you have proof it has just been done Will cost around £200 to get someone to do or £100 if you do it yourself but can save you 1k in the long run. Just had a thought..if it has had ss valves put in then the correct springs MUST be used(different valve weights) if the springs haven't been changed that causes a similar effect to bounce Link to comment Share on other sites More sharing options...
CMSMJ1 Posted February 8, 2013 Report Share Posted February 8, 2013 Get the head off it chap - let the dog see the rabbit. I smashed a piston crown in on my NC30 - I was very obvious.. These pieces were under the rocker cover Link to comment Share on other sites More sharing options...
Chrisa112 Posted February 9, 2013 Author Report Share Posted February 9, 2013 OK, found enough time to get the cam shaft assembly off. Both the shims that I found laying on the head were from both exhaust valves. Intake shims were still there and fine. Also, at TDC I can see all four valves through the springs. I guess the piston could be holding up any dodgy valves but so far I'm thinking both exhaust valve shims just sprung out and caused the combustion process to go to shit, thus cutting the engine. Of course I could be talking complete bollocks as this is the first engine I've properly had apart Head off tomorrow. Link to comment Share on other sites More sharing options...
Chrisa112 Posted February 10, 2013 Author Report Share Posted February 10, 2013 Well, its pretty fucked. What came out of exhuast: Piston, intake side: Piston exhaust side: Piston, top, exhaust valves hit. So over all its pretty bad. Lots of tiny metal bits down and around the crank. More pics to follow. Dont understand what has happened really. Other than the piston has somehow moved around inside the barrel enough to bend in the edges of the piston. Could oil starvation have caused this? If not, what's everyones thoughts. Cheers! Link to comment Share on other sites More sharing options...
CMSMJ1 Posted February 10, 2013 Report Share Posted February 10, 2013 Ouch. Cracking pictures though.. It is voodoomagic that engines actually work at all Link to comment Share on other sites More sharing options...
stuntmonkee Posted February 10, 2013 Report Share Posted February 10, 2013 What happenedon my CRF was half the carb slide cracked off and went down the inlet, resulting in chaos very similar to that - I guarentee your conrod is fucked too... Link to comment Share on other sites More sharing options...
fontyyy Posted February 10, 2013 Report Share Posted February 10, 2013 I thought Honda's didn't go bang? Surely it's an electrical problem ?? TBF, it is a proper full on race bike with a 15 hour bottom end service schedule I don't like to ask how far past that you'd gone Link to comment Share on other sites More sharing options...
Chrisa112 Posted February 10, 2013 Author Report Share Posted February 10, 2013 TBF, it is a proper full on race bike with a 15 hour bottom end service schedule I don't like to ask how far past that you'd gone Well I've no idea as no one has EVER said that its a 15hour bottom end service. Unsure whether to just sort the top end or look for a new engine. Link to comment Share on other sites More sharing options...
Superdunc Posted February 10, 2013 Report Share Posted February 10, 2013 It should be in the manual, generally such schedules only apply to race use. Trouble is when you convert CRFs KTMs YZFs etc to supermoto spec and use them on the road, they get a harder time than if you were racing in a world championship enduro. You're now well aware of the results. With regards to a rebuild. The Rod and bottom end bearings will be knackered, even if the look servicable, repairing the motor with out rebuilding the bottom end will be a waste of time. Buying a second hand engine will be like russian roulette. It looks like the the heads didn't come of the valves so the head should be salvageable, at a minimum you'll need a set of valves, springs and retainers, Piston, con rod kit, full crank rebuild, cam chain, and a replated?rebored barrel. Sounds a lot but probably cheaper than an unknow second hand engine. Sorry for the bad news, but that I've seen worse. Link to comment Share on other sites More sharing options...
GTR Racer Posted February 10, 2013 Report Share Posted February 10, 2013 Should of just gotten a 2 stroke Chris ha Link to comment Share on other sites More sharing options...
porter_jamie Posted February 10, 2013 Report Share Posted February 10, 2013 You want to sell it? Link to comment Share on other sites More sharing options...
Chrisa112 Posted February 10, 2013 Author Report Share Posted February 10, 2013 You want to sell it? Urm...No. Link to comment Share on other sites More sharing options...
Chrisa112 Posted February 10, 2013 Author Report Share Posted February 10, 2013 It should be in the manual, generally such schedules only apply to race use. Trouble is when you convert CRFs KTMs YZFs etc to supermoto spec and use them on the road, they get a harder time than if you were racing in a world championship enduro. You're now well aware of the results. With regards to a rebuild. The Rod and bottom end bearings will be knackered, even if the look servicable, repairing the motor with out rebuilding the bottom end will be a waste of time. Buying a second hand engine will be like russian roulette. It looks like the the heads didn't come of the valves so the head should be salvageable, at a minimum you'll need a set of valves, springs and retainers, Piston, con rod kit, full crank rebuild, cam chain, and a replated?rebored barrel. Sounds a lot but probably cheaper than an unknow second hand engine. Sorry for the bad news, but that I've seen worse. Nope not noted in the Honda service manual. Nothing about the bottom end in the maintenance schedule, it just says to replace piston & rings, E & T oil and filter at 15 hours. And to check valve clearances. I had not done this yet I'd only put about 5 hours (MAX) of riding time on the bike. Bike was received with 25 (or so) hours of riding time on the clock and it was running well according to the previous owner...who I trusted. Could this damage be down to purely lack of oil? As I said, the engine oil window was empty when I pulled over at the side of the road! :/ I did notice in the service manual that it rough idle can be due to lack of piston compression and it had been slightly dodgy idle (randomly died a few times after putting choke it and idling fine without it for a few mins). Could this have had a factor? So all valves are intact and undamaged and moving freely in the guides? Valves are damaged, but still intact. Unsure about moving freely in the guides. See pics in post below for valve condition. As you guys probably realised. I've not had an engine blow up on me before or had an engine in this many bits. So this forum is my kinda lifeline at the mo... Thanks again. Link to comment Share on other sites More sharing options...
Chrisa112 Posted February 10, 2013 Author Report Share Posted February 10, 2013 Link to comment Share on other sites More sharing options...
Chrisa112 Posted February 10, 2013 Author Report Share Posted February 10, 2013 Link to comment Share on other sites More sharing options...
speedy sie Posted February 10, 2013 Report Share Posted February 10, 2013 nice i seen a few sprint bike top fuel pistons looking like that mine ran 20;1 top fuel and ofter pushed the ring down...wisco did there best to help me out but still had the odd over rev and wup...pistion looking a bit like that ...and this was a2 stroke!..the old rm250f piston Link to comment Share on other sites More sharing options...
Superdunc Posted February 10, 2013 Report Share Posted February 10, 2013 That motor was about 3 revoloutions from completly destroying itself. Lack of oil? probably not. they don't hold a lot of oil anyway, so the lack oil in the site glass was due to it all blowing out the exhaust. I'm going to disagree with Mille here and suggest that it was either piston skirt failure, or possibly big end. Either would allow the piston to hit the exhuast valves and bend them. The valves will open less if you lose the shims, but if you bend the valves they won't close fully causing the clearances to open up and allowing the shims to jump out. These bikes are not designed for being held flat out on the roads for mile after mile, they are great fun when you do but there is a cost. Link to comment Share on other sites More sharing options...
porter_jamie Posted February 10, 2013 Report Share Posted February 10, 2013 Have you priced up a new barrel crank/rods piston valves guides rockers and shim plus gaskets yet? Link to comment Share on other sites More sharing options...
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